Newark is the third-largest hub for United Airlines (after Chicago–O'Hare and Houston–Intercontinental), which is the airport's largest tenant (operating within all of Terminal C and part of Terminal A). Newark's second-largest tenant is FedEx Express, whose third-largest cargo hub uses three buildings on two million square feet of airport property.[7] During the 12-month period ending in July 2014, over 68% of all passengers at the airport were carried by United Airlines.[8]

Newark was the busiest commercial airport in the world until LaGuardia Airport opened in December 1939; the March 1939 Official Aviation Guide shows 61 weekday departures on five airlines, but by mid-1940 passenger airlines had all left Newark.[12][13]

On December 16, 1951 a Miami Airlines C-46 bound for Tampa lost a cylinder on takeoff from runway 28 and crashed in Elizabeth killing 56.[14] On January 22, 1952 an American Airlines CV-240 crashed in Elizabeth, while on approach to runway 6 killing all 23 aboard and seven on the ground.[15] On February 11, 1952 a National DC-6 crashed in Elizabeth after takeoff from runway 24, killing 29 of 63 on board and four on the ground.[16] Inevitably, the airport was closed for some months; airline traffic resumed later in the year, but the airport's continued unpopularity and the New York area's growing air traffic led to searches for new airport sites. A proposal to build a new airport at what is now the Great Swamp National Wildlife Refuge was defeated by local opposition.

The April 1957 Official Airline Guide showed 144 weekday passenger fixed-wing departures from Newark: 40 Eastern, 19 Capital, 16 American, 14 United, 14 Mohawk, 13 Allegheny, 11 TWA, 8 National, 5 Delta and 4 Braniff. National had a nonstop to Miami, Eastern had nonstops to Miami, New Orleans and Houston, Braniff had a nonstop DC-7C to Dallas and TWA flew nonstop to St Louis; no other nonstops to points west of St. Louis and no international nonstops.[17] (Eastern started a nonstop to Montreal in 1958, probably Newark's first scheduled international nonstop since 1939, though Eastern had nonstops to San Juan in 1951.) Jet airliners arrived in 1961. In 1964, American and TWA started flying nonstop to California, although Newark's longest runway remained only 7,000 ft (2,100 m) until 1970. TWA's 707 nonstop to Heathrow in 1978 was probably Newark's first trans-Atlantic nonstop.

In the 1970s, the airport became Newark International Airport. Present Terminals A and B opened in 1973, although some charter and international flights requiring customs clearance remained at the North Terminal. The main building of Terminal C was completed at the same time, but only metal framing work was completed for the terminal's satellites. It lay dormant until the mid-1980s, when for a brief time the west third of the terminal was equipped for international arrivals and used for some People Express transcontinental flights. Terminal C was finally completed and opened in June 1988.

Underutilized through the 1970s, Newark expanded dramatically in the 1980s. People Express struck a deal with the Port Authority to use the North Terminal as both its air terminal and corporate office in 1981 and began operations at Newark that year. It grew quickly, increasing Newark's traffic through the 1980s.[18]Virgin Atlantic began service between Newark and London in 1984, challenging JFK's status as New York's international gateway (but Virgin Atlantic now has more flights at JFK than at Newark). Federal Express (now known as FedEx Express) opened its second hub at the airport in 1986.[7] When People Express merged into Continental in 1987, operations (including corporate office operations) at the North Terminal were reduced and the building was demolished to make way for cargo facilities in the early 1990s. This merger started Continental's and later United Airlines', dominance at Newark Airport.

In late 1996, the monorail was opened, connecting all three terminals, the overflow parking lots and garages, and the rental car facilities. A brand new International Arrivals Facility also opened in Terminal B that year.[9] The monorail was expanded to the new Newark Airport train station on Amtrak's Northeast Corridor line in 2001 and was renamed AirTrain Newark.

After the hijacking of United Airlines Flight 93 in the September 11, 2001 attacks while en route from Newark to San Francisco, the airport's name was changed from Newark International Airport to Newark Liberty International Airport in 2002. This name was chosen over the initial proposal, Liberty International Airport at Newark, and pays tribute both to the victims of the 9/11 attacks, but also to the landmark Statue of Liberty, just 7 miles (11 km) east of the airport.[19][20]

A modern control tower was constructed in 2002 and entered service in 2003, becoming the fourth and tallest tower in the airport's history, standing 325 feet over the main parking lot.[9]

United (then Continental) began flying from Newark to Beijing on June 15, 2005 and to Delhi on November 1, 2005. The airline soon started flights to Mumbai. Continental/United's EWR-BOM has been and continues to be the only U.S. carrier to serve India nonstop from the United States, the third U.S. carrier after United and Northwest to serve mainland China nonstop and the only U.S. carrier with nonstop flights to Beijing from the New York City area. On July 16, 2007 Continental announced it would seek government approval for nonstops between Newark and Shanghai in 2009. Continental began flights to Shanghai from Newark on March 25, 2009, using Boeing 777-200ER aircraft. Newark was the only New York area airport used by Philippine Airlines, until financial problems in the late 1990s caused it to terminate this service. However, once PAL resumes flights to New York in 2015, it will begin service to JFK and not Newark, following the removal of the Philippines from the air safety blacklist of the Federal Aviation Administration (FAA) on Thursday, April 10.[21]

In June 2008, flight caps were put in place to restrict the number of flights to 81 per hour. The flight caps, in effect until 2009, were intended to be a short-term solution to Newark's congestion. The FAA has since embarked on a seven-year-long project to reduce congestion in all three New York area airports and the surrounding flight paths.[22]

Newark is a major hub for United Airlines (previously Continental Airlines before the 2010-12 merger). United has its Global Gateway at Terminal C, having completed a major expansion project that included the construction of a new, third concourse and a new Federal Inspection Services facility. With its Newark hub, United is the largest provider of air service to the New York metropolitan area. On March 6, 2014 United opened a new 132,000-square-foot (12,300 m2), $25 million maintenance hangar on a 3-acre (1.2 ha) parcel in order to accommodate United's wide body aircraft during maintenance.[23] In 2015, the airline announced plans to leave JFK altogether and streamline its transcontinental operations at Newark.[24]

Runway 11/29 is one of the three runways built during World War II. In 1952 Runways 1/19 and 6/24 were closed and a modern Runway 4/22 (now 4R/22L) opened at a length of 7,000 ft (2,100 m) After 1970 this runway was extended to 9,800 feet (3,000 m), shortened for a while to 9,300 ft (2,800 m) and finally reached its present length by 2000. Runway 4L/22R opened in 1970 at a length of 8,200 ft (2,500 m) and was extended to its current length by 2000.

Runway 4L/22R is primarily used for takeoffs while 4R/22L is primarily used for landings and 11/29 is used by smaller aircraft or when there are strong crosswinds on the two main runways. Newark's parallel runways (4L and 4R) are 950 feet (290 m) apart, the fourth smallest separation of major airports in the U.S., after SFO, LAX and SEA.

Newark Liberty International Airport has three passenger terminals. Terminal A and Terminal B were completed in 1973 and have four levels. Ticket counters are on the top floor, except for the second-floor Air India and first-floor British Airways desks in Terminal B. Gates and shops are on the third floor. Baggage carousels (both A and B) are on the second floor and Terminal B has an international arrivals lounge on that floor too. Finally, short-term parking and ramp operations (restricted areas) are on the ground floor.

Terminal A handles all non-United domestic, Canadian and some United Express (i.e. ultra-short haul flights) flights; Terminal B exclusively handles foreign carriers and the short-haul Delta Connection flights, and Terminal C is exclusively for United Airlines and its short haul carrier United Express.

Terminal C, designed by Grad Associates[27] and completed in 1988, has two ticketing levels, one for international check-in and one for domestic check-in. The main terminal building for Terminal C was built alongside Terminals A and B in the 1970s, but lay dormant until People Express Airlines took it over as a replacement for the former North Terminal when the airline's hub there outgrew the old facility. Upon opening, Terminal C had 41 gates, originally with one departures level, one arrivals level and an underground parking garage. The gates, as well as food and shopping outlets, are located on a mezzanine level between the two check-in floors.

From 1998 to 2003, Terminal C was rebuilt and expanded in a $1.2 billion program known as the Continental Airlines Global Gateway Project.[28] The project, which was designed by Skidmore, Owings & Merrill,[28] doubled the available space for outbound travelers as the former baggage claim/arrivals hall was remodeled and turned into a second departures level. Probably most significant was the addition of International Concourse C-3, a spacious and airy new facility with capacity for a maximum of 19 narrowbody aircraft (or 12 widebody planes). Completion of this new concourse brought Terminal C's total number of mainline jet gates to 57. Concomitant with Concourse C-3 is a new international arrivals facility. Also included in the project: a 3,400-space parking garage constructed in front of the terminal, a new airside corridor connecting Concourses C-1, C-2 and C-3, a new President's Club (now called United Club) lounge between C-2 and C-3, and all-new baggage processing facilities, including reconstruction of the former underground parking area into a new baggage claim and arrivals hall.

In 2008, Terminal B was renovated to increase capacity for departing passengers and passenger comfort. The renovations included expanding and updating the ticketing areas, building a new departure level for domestic flights and building a new arrivals hall.[29] Plans are also in place to expand Terminal A by adding a new parking garage and radically expanding the size of the first concourse to add new gates, ticketing, baggage and security areas.

Each terminal has three concourses: Terminal A, for instance, is divided into concourses A1, A2 and A3. Gate numbering is continuous through all the terminals. Wayfinding signage throughout the terminals was designed by Paul Mijksenaar, who also designed signage for LaGuardia and JFK Airports.[30]

Terminal A is the only terminal having no immigration facilities: flights arriving from other countries cannot use Terminal A (except countries with US customs preclearance), although some departing international flights use the terminal.

Following the business model of the Port Authority's other facilities, in some cases entire terminals are operated by terminal operators and not by the Port Authority directly. At Newark Liberty, Terminal A and Terminal C are operated by United Airlines. Terminal B is the only passenger terminal directly operated by the Port Authority.

In January 2012, Port Authority executive director Patrick Foye said $350 million would be spent on Terminal B, addressing complaints by passengers that they cannot move freely. That renovation is currently underway. Foye also said a new Terminal A may be built.[31]

Further developments were made in Terminal B when the Port Authority installed new LED fixtures in 2014. The LED fixtures developed by Sensity Systems, use wireless network capabilities to collect and feed data into the software that can spot long lines, recognize license plates as well as identify suspicious activity and alert the appropriate staff.[32]

In November 2014, airport amenity manager OTG announced a new $120 million renovation plan for terminal C that includes installing 6,000 iPads as well a 55 new restaurants headed by celebrity chefs, with the first new restaurants opening in summer of 2015 and the whole project completed in 2016.[33]

Private limousine, car service, and taxis also provide service to/from the airport. Taxis serving the airport charge a flat rate based on destination. For trips to/from New York, fares are set by the New York City Taxi and Limousine Commission.

Within the Newark Liberty International Airport complex is a Marriott hotel, the only hotel located on airport property.[55] Shuttle vans operate between the hotel and terminals because the Marriott is not serviced by the monorail and there is no official walking route to the terminals, despite the Marriott's immediate proximity to the main parking lot between the terminals.

Newark Airport, along with LaGuardia and Kennedy airports, uses a uniform style of signage throughout the airport properties. Yellow signs direct passengers to airline gates, ticketing and other flight services; green signs direct passengers to ground transportation services and black signs lead to restrooms, telephones and other passenger amenities.

The airport has the IATA designation EWR, rather than a designation that begins with the letter 'N' because the obvious designator of "NEW" is already assigned to Lakefront Airport in New Orleans, LA, and because the Department of the Navy uses three-letter identifiers beginning with N for its purposes.[56]

The airport has no official area to view flight traffic, but the IKEA of Elizabeth (located on the East side of the New Jersey Turnpike) may be used as an unofficial vantage point for aircraft both departing and landing.

On March 17, 1929, a Colonial Western AirlinesFord Tri-Motor suffered a double engine failure during its initial climb after takeoff, failed to gain height, and crashed into a railroad freight car loaded with sand, killing 14 of the 15 people on board. At the time, it was deadliest aviation accident in American history.[57]

On December 16, 1951, a passenger C-46 Commando lost a cylinder on takeoff from Runway 28 and crashed in Elizabeth, New Jersey, killing 56.

In the September 11, 2001 attacks, United Airlines Flight 93 from Newark to San Francisco was hijacked, but the passengers revolted, forcing the hijackers to crash the aircraft into an empty field in Shanksville, Pennsylvania. Based on the direction the plane was flying at the time and information gathered afterward, most observers believe that the hijackers intended to crash the plane into a target in Washington, D.C., such as the Capitol or White House.[61] A flag now flies over Gate A17, the gate from which the flight pushed back that day.[62]

On January 10, 2010, United Airlines Flight 634, an Airbus A319, made an emergency landing after the aircraft's right main landing gear failed to deploy. No passengers or crew members were injured during the landing.[64] The aircraft sustained substantial damage in the accident.[65]

On January 21, 2013, United Airlines Flight 4480 from Rochester, New York, was landing when several rear tires blew. The plane veered onto a taxiway, but did not strike anything. The plane was carrying eight passengers and five crew members. No one was hurt.[66]

^"Newark Liberty International Airport is an airport of firsts: the first major airport in the New York metropolitan area, the first with a control tower and now the area's busiest. Sandwiched between the New Jersey Turnpike, U.S. Routes 1 and 9, and I-78, the airport handles more flights (though not as many passengers) as Kennedy International Airport, despite being 40 percent of Kennedy's land size. The airport serves as a hub for United Airlines, among 50 other scheduled carriers. The City of Newark built the airport on 68 acres (28 ha) of marshland in 1928 and the Army Air Corps operated the facility during World War II. After the Port Authority took it over in 1948, an instrument runway, a terminal building, a control tower and an air cargo center were added. The airport's original 1935 central terminal building is a National Historic Landmark. Newark Liberty employs more than 24,000 people." Ken Belson, "Newark Liberty International Airport (NJ)" The New York Times July 10, 2008